Camera utilizing detection of visual line

ABSTRACT

A camera includes an electronic viewfinder adapted to electrically display a photographing image, a visual line detection unit for detecting the position of a camera operator&#39;s visual line on a picture plane of the electronic viewfinder, and a display processing unit for displaying on the electronic viewfinder a photographing-related information involved in a camera photographing. In such a camera, the display processing unit controls a display position of the photographing-related information in accordance with an output of the visual line detection unit.

This is a continuation application under 37 CFR 1.62 of priorapplication Ser. No. 08/598,463, filed Feb. 8, 1996, now abandoned whichis a divisional of Ser. No. 08/272,903, filed Jul. 8, 1994 (U.S. Pat.No. 5,570,156) ; which is a continuation of Ser. No. 07/934,121, filedAug. 21, 1992, abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a camera in which a camera operator'svisual line (line of sight) is detected to be utilized.

2. Description of the Related Art

As an example of such a camera, explained hereinafter is a video cameraprovided with an electronic viewfinder adapted to display aphotographing image.

In such type of conventional video camera having an electronicviewfinder adapted to display a photographing image on a small-sizeddisplay implemented by, for instance, liquid crystal display elements, acamera operator is obliged to perform the operation for functionalinputs through switches or the like, while peeping through theelectronic viewfinder, if he or she wishes to perform the operation forfunctional inputs under photographing.

FIGS. 15A and 15B show is a view showing, by way of example, a pictureplane display of an electronic viewfinder unit of the conventional videocamera. In a periphery of a camera subject image, for operator's sake,there are selectively displayed, together with the camera subject image,various kinds of information necessary for the operation of the videocamera, for example, photographing mode information (focus, shutter,white balance mode information, etc.), camera operation information(under photographing, standby, stop, etc.), camera defective information(dew condensation, etc.), power source information (battery exhaustionwarning, etc.) and tape information for recording images (remainingeffective time of tape, etc.).

According to such a display, however, information such as various modesdisplay and warning display is indicated or displayed in small size atperipheral edges or corners of the picture plane of the electronicviewfinder. Hence, the operator will be obliged to shift his or hervisual line from the camera subject to the periphery and thus willencounter the fear of losing a picture recording timing or a shutteropportunity. Further, there still remains a problem such that thedisplay of information is hard to read, thereby causing the informationto be overlooked.

Furthermore, when the operator sets up the various photographing modesand the like, he or she has to once take his or her eye off theviewfinder for the purpose of seeing and operating various functionswitches provided on a surface of the camera main body. As a result, itwill be the cause of disturbance of the image plane or picture plane andof losing sight of the camera subject.

Recently, there is a tendency such that various functions associatedwith the video camera are increasing owing to the variety in user'sapplication or usage, while miniaturization of the video camera isprogressing. In the light of such a tendency, the foregoing problemsbecome serious.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a cameracapable of setting up photographing conditions while confirming thesame, without taking an operator's eye off a camera subject imagedisplayed on an electronic viewfinder.

To achieve the above-described object, according to one aspect of thepresent invention, there is provided a camera, which comprises anelectronic viewfinder adapted to electrically display a photographingimage, a visual line detection means for detecting the position of acamera operator's visual line on a picture plane of the electronicviewfinder, and a display processing means for displaying on theelectronic viewfinder a photographing-related information involved in acamera photographing, wherein the display processing means controls adisplay position of the photographing-related information in accordancewith an output of the visual line detection means.

It is another object of the present invention to provide a camera withan improved detection accuracy of the visual line detection means.

To achieve the above-described object, according to another aspect ofthe present invention, there is provided a camera, which comprises anelectronic viewfinder adapted to electrically display a photographingimage, and a visual line detection means for detecting the position of acamera operator's visual line on a picture plane of the electronicviewfinder, wherein a spectral characteristic of light emitted from adisplay means of the electronic viewfinder is set to a spectralcharacteristic having no influence on light emitted from an illuminationmeans for visual line detection included in the visual line detectionmeans.

The objects, features and advantages of the present invention willbecome more apparent from the following detailed description ofpreferred embodiments of the present invention, taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a block diagram schematically showing the arrangement of avisual line detection system to which one embodiment of the presentinvention is applied;

FIG. 2 is a schematic view illustrating intensity of an output signalfrom a photo-electric element array shown in FIG. 1;

FIG. 3 is a block diagram schematically showing an arrangement ofessential portions of a video camera according to the first embodimentof the present invention;

FIGS. 4A and 4B show a view useful for understanding display on thefinder picture plane in the first embodiment;

FIG. 5 is a perspective view schematically showing an arrangement ofessential part of the visual line detection system shown in FIG. 3;

FIGS. 6(A) and 6(B) each are a schematic view useful for understandingan optical principle shown in FIG. 5;

FIGS. 7(A) and 7(B) each are an explanatory view illustrating areflected image on planes of the photo-electric element array accordingto the first embodiment;

FIG. 8 is a sequence flow chart useful for understanding a visual linedetection operation of the visual line detection system according to thefirst embodiment;

FIG. 9 is a view depicting an intensity of an output signal of thephoto-electric element array into which noise is mixed;

FIG. 10 is a view depicting a spectral characteristic involved in thefinder picture plane using a black-and-white small Braun tube of displaymeans and a spectral characteristic of light emitted from an infraredlight emitting diode, according to the instant embodiment;

FIG. 11 is a view depicting a spectral characteristic of light emittedfrom a finder picture plane using a color liquid crystal display and aspectral characteristic of light emitted from the infrared lightemitting diode, according to the instant embodiment;

FIG. 12 is a block diagram schematically showing an arrangement ofessential portions of a video camera according to the second embodimentof the present invention;

FIG. 13 is a sequence flow chart for detection of the visual lineaccording to the second embodiment;

FIG. 14 is an explanatory view illustrating a reflected image from theeyeball projected on planes of the photo-electric element array,according to the second embodiment; and

FIGS. 15A and 15B show a view useful for understanding a picture planedisplay of an electronic viewfinder unit of the conventional videocamera.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Preferred embodiments of the present invention will be described withreference to the accompanying drawings.

First, described is a principle of a detection method of detecting as towhere an observer or operator observes on an observation face, i.e., aso-called visual line (visual axis).

According to the instant embodiment, parallel pencil of rays from alight source is projected to a front portion of an observer's eyeball,and a position of a cornea-reflected image by a reflected light from hisor her cornea and an image formation position of his or her pupil aredetected to obtain the visual axis.

FIGS. 1 and 2 are views useful for understanding a principle of visualline detection method. FIG. 1 is a block diagram schematically showingthe arrangement of a visual line detection optical system, and FIG. 2 isa schematic view illustrating intensity of an output signal from aphoto-electric element array 6 shown in FIG. 1.

In FIG. 1, reference numeral 5 denotes a light source such as lightemitting diode adapted to irradiate infrared light which is insensitivefor observers. The light source 5 is disposed at a focal plane of alight projection lens 3.

The infrared light emitted from the light source 5 passes through thelight projection lens 3 in the form of parallel pencil rays and is thenreflected by a half-mirror 2 to illuminate a cornea 21 of an eyeball201.

At that time, the cornea-reflected image d which is formed by part ofthe infrared light beams reflected from a surface of the cornea 21, istransmitted through the half-mirror 2 and then focussed by a lightreceiving lens 4, so that the image d is re-formed at a position Zd' onthe photo-electric element array 6.

Pencil of rays from edge portions a and b of an iris 23 is transmittedthrough the half-mirror 2 and the light receiving lens 4, so that imagesassociated with the edge portions a and b are formed at positions Za'and Zb' on the photo-electric element array 6, respectively.

Assuming that the rotation angle θ of an optical axis (ii) of theeyeball 201 with respect to an optical axis (i) of the light receivinglens 4 is small, if the Z coordinates of the edge portions a and b ofthe iris 23 are denoted by Za and Zb, respectively, the Z coordinate Zcof the center c of the iris 23 is represented by:

    Zc=(Za+Zb ) /2

If the Z coordinate of a generating position of the cornea-reflectedimage d, and a distance between the center of curvature O of the cornea21 and the center c of the iris 23 are denoted by d and Oc,respectively, the rotation angle θ of the optical axis (ii) of theeyeball 201 substantially satisfies the following equation:

    Oc ×sin θ=Zc-Zd                                (1)

Here, the Z coordinate Zd of the generating position of thecornea-reflected image d and the Z coordinate of the center of curvatureO of the cornea 21 are coincident with each other. Consequently, in anarithmetic operation means 9, it is possible to obtain the rotationangle θ of the optical axis (ii) of the eyeball 201 by detectingpositions of the respective singular points (cornea-reflected image, andimages associated with the edge portions a and b of the iris) projectedon the photo-electric element array 6 as shown in FIG. 2. Here, theequation (1) is replaced by the following equation:

    β×Oc×sinθ0 =(Za'+Zb')/2 -Zd'        (2)

wherein β denotes a magnification of image formation which is determinedby the distance L1 between the generating position of thecornea-reflected image d and the light receiving lens 4 and the distanceL between the light receiving lens 4 and the photo-electric elementarray 6, and usually takes an approximately constant value.

A video camera according to the first embodiment of the presentinvention, to which the above-mentioned visual line detection scheme isapplied, will be described in detail referring to FIGS. 3-9.

FIG. 3 is a block diagram schematically showing an arrangement ofessential portions of a video camera according to the first embodimentof the present invention, wherein the same parts are denoted by the samereference numerals as those of FIG. 1.

In FIG. 3, reference numeral 1 denotes an ocular or eyepiece; 2 ahalf-mirror which also serves as a beam splitter forvisible-light-transmission/infrared-light-reflection; 4 a lightreceiving lens; 5 an illumination means comprising, for example, lightemitting diodes; and 6 a photo-electric element array. The lightreceiving lens 4 and the photo-electric element array 6 constitute partof light receiving means.

As the photo-electric element array 6, usually, there is used a devicein which a plurality of photo-electric elements are arrangedperpendicularly to the drawing on a one-dimension basis, but ifnecessary, it is possible to use a device in which a plurality ofphoto-electric elements are arranged on a two-dimension basis.

These structural elements 1, 2, 4, 5 and 6, as mentioned above,constitute a visual line detection system for an operator's orobserver's eyeball 201.

Further, in FIG. 3, reference numeral 101 denotes an electronicviewfinder (EVF); and 102 a finder picture plane of the electronicviewfinder 101 using a black-and-white small Braun tube.

In this instance, a projection image appearing on the finder pictureplane 102 is introduced via the eyepiece 1 to an eye point E.

A visual line detection means according to the present embodimentcomprises the visual line detection system implemented by theabove-mentioned structural elements 1, 2, 4, 5 and 6, and part of afixation point position detection circuit 109 as an arithmetic operationmeans, that is, an eyeball optical axis detection circuit, an eyeballdetermining circuit, a visual axis correction circuit and a fixationpoint detection circuit.

In the visual line detection system, infrared light radiated from aninfrared light emitting diode (IRED) 5 illuminates an observer's eyeball201 near the eye point E.

The infrared light reflected from the eyeball 201 is reflected at thehalf-mirror 2 and then converged through the light receiving lens 4 soas to form an image on the photo-electric element array 6.

The fixation point position detection circuit 109 carries out a fixationpoint detection with software of a microcomputer on the basis of asignal outputted from the photo-electric element array 6.

The fixation point position is the position of a camera operator'svisual line on the finder picture plane 102 of the electronic viewfinder101.

Reference numeral 103 denotes a fixation point display processingcircuit for mixing a video signal outputted from a video signalprocessing circuit 106 with an indication of fixation point informationoutputted from the fixation point position detection circuit 109. If itis desired that the operator's fixation point is displayed on the finderpicture plane 102, it is set up by a mode switch (not illustrated).

Reference numeral 104 denotes a warning display circuit adapted tooutput to the fixation point display processing circuit 103, ifnecessary, information which ought to be known to a video cameraoperator, for example, a warning indicating that a remaining amount oftape is little, a warning indicating that a remaining amount of batterypower is little, or the like. The warning display circuit 104 serves todisplay such warning information on the finder picture plane 102 underthe control of the fixation point display processing circuit 103.

Reference numeral 105 denotes a recording circuit for generating arecording signal for recording on a recording medium; and 106 a videosignal processing circuit for converting an image pickup signal formedby a CCD (image pickup device) 110 into a predetermined video signal.

Reference numeral 107 denotes an automatic exposure (AE) circuit for anexposure control; 108 an automatic focusing (AF) circuit for anautomatic focusing control; 113 a focus motor; 110 a CCD for imagesensing; 111 a lens diaphragm; and 112 a lens group.

An image obtained through the lens group 112 is picked up via the lensdiaphragm 111 on the CCD 110.

A signal outputted from the CCD 110 is fed via the video signalprocessing circuit 106 to the recording circuit 105.

Further, the output signal obtained from the CCD 110 is applied to theAE circuit 107 and the AF circuit 108 to perform a detection ofbrightness or luminance of the image and an edge detection, so as tocontrol the diaphragm 111 and the focus motor 113, respectively.

An output signal of the video signal processing circuit 106 is mixed, inthe fixation point display processing circuit 103, with informationrepresenting an operator's fixation point position from the fixationpoint position detection circuit 109, and then displayed on the finderpicture plane 102.

When a warning indication signal is outputted from the warning displaycircuit 104, the fixation point display processing circuit 103 mixes thevideo signal with the warning indication signal, and then provides awarning indication on the finder picture plane 102 of the electronicviewfinder 101. The warning indication on the finder picture plane 102is implemented at a fixation point position outputted from the fixationpoint position detection circuit 109. FIGS. 4A and 4B show an example ofthe display on the finder picture plane 102 when the warning indicationis implemented, wherein a battery exhaustion warning "BATT" is indicatedat part of a person image on which the operator fixes his or her eye.

The fixation point information obtained from the fixation point positiondetection circuit 109 is fed to the fixation point display processingcircuit 103, and to the AE circuit 107 and the AF circuit 108 as well tobe used for area set up for extracting video signals near the fixationpoint in order to implement the AE/AF controls to the neighborhood ofthe fixation point.

Now, a method of detecting an operator's visual line (fixation point)according to the embodiment of the present invention will be describedin detail referring to FIGS. 5-8.

FIG. 5 is a perspective view schematically showing an arrangement ofessential part of the visual line detection system shown in FIG. 3.FIGS. 6(A) and 6(B) each are a block diagram useful for understanding anoptical principle of the visual line detection system.

Infrared light emitting diodes 5a, 5b and 5c for use in illumination areused to detect a distance between a camera and an operator's eyeball,making a pair of two pieces. In accordance with a camera figure orposture, a pair of infrared light emitting diodes 5a and 5b is used todetect a horizontal position, and a pair of infrared light emittingdiodes 5b and 5c is used to detect a vertical position.

While FIG. 5 and FIGS. 6(A) and 6(B) show no means for detecting acamera figure, the camera figure is detected by utilizing a mercuryswitch or the like.

The infrared light emitting diodes 5a and 5b are disposed at therespective positions shifted in an arrayal direction (Z axis direction)of the photo-electric element array 6 with respect to an optical axis (Xaxis) of the light receiving lens 4 and in a direction perpendicular tothe arrayal direction (Z axis direction) of the photo-electric elementarray 6.

In FIG. 6(A), pencil of rays from the infrared light emitting diodes 5aand 5b disposed separately in an arrayal direction (Z axis direction) ofthe photo-electric element array 6 forms cornea-reflected images e and dat positions separated from each other in a Z axis direction,respectively.

Here, the Z coordinate of a middle point between the cornea-reflectedimages e and d and the Z coordinate of the center of curvature of thecornea 21 are coincident with each other.

A distance between the cornea-reflected images e and d is varied incorrespondence with a distance between the infrared light emittingdiodes 5a, 5b and the observer's eyeball 201. Consequently, it ispossible to obtain the image-formation magnification β of each of thecornea-reflected images by detecting the positions of cornea-reflectedimages e' and d' re-formed on the photo-electric element array 6.

In FIG. 6(B), the infrared light emitting diodes 5a and 5b (not shown)disposed in a direction perpendicular to the arrayal direction of thephotoelectric element array 6 irradiate an observer's eyeball from thediagonal upper direction. Hence, if an observer's eyeball does notrotate in a vertical direction (within an X-Y plane), thecornea-reflected image e (d not shown) is formed with displacement in a(+) Y direction in the drawing apart from the center of curvature of thecornea 21 and the center of the pupil 24.

FIG. 7(A) is an explanatory view illustrating a reflected image from theeyeball projected on planes of a plurality of photo-electric elementarrays of the photo-electric element array 6, which shows the reflectedimage from the eyeball projected on the photo-electric element array 6.In FIG. 7(A), the cornea-reflected images e' and d' are re-formed on aphoto-electric element array Yp'. FIG. 7(B) shows an output signalobtained from the photo-electric element array Yp'.

Next, a visual line detection operation of the above-mentioned visualline detection system will be described referring to a sequence flowchart of FIG. 8.

First, in step S1, an eyeball optical axis detection circuit included inthe fixation point position detection circuit 109 detects a rotationangle of an eyeball optical axis. Next, image signals of thephoto-electric element array 6 are read out in turn from a (-) Ydirection shown in FIG. 7(A), so as to detect a photo-electric elementarray (line) Yp' on which the cornea-reflected images e' and d' arere-formed.

In step S2, detected is the positions Zd' and Ze' of thecornea-reflected images e' and d in the arrayal direction.

In step S3, the image-formation magnification β of the optical system isobtained from an interval (|Zd'-Ze'|) between the cornea-reflectedimages e' and d.

In step S4, boundary points Z2a' and Z2b' between the iris 23 and thepupil 24 are detected on the photo-electric element array (line) Yp'.

In Step S5, calculated is a pupil length (|Z2a'-Z2b'|) on thephoto-electric element array (line) Yp'.

In step S6, as shown in FIG. 7(A), usually, the photo-electric elementarray Yp' on which the cornea-reflected image are formed is generatedwith displacement in a (-) Y direction in the drawing apart from aphoto-electric element array Y0' in which the center c' of the pupil 24exists, and another photo-electric element array Y1' to be subjected toread-out of the image signal is computed on the basis of theimage-formation magnification β and the pupil length. Here, thephoto-electric element array Y1' is established at the position wellaway from the photo-electric element array Yp'.

Likewise, in step S7, upon detecting the boundary points Z1a' and Z1b'between the iris 23 and the pupil 24 on the photo-electric element arrayY1', a position (Zc', Yc') of the center c' of the pupil 24 is obtainedby using, among from the boundary points (Z1a', Y1'), (Z1b', Y1'),(Z2a', Yp'), and (Z2b', Yp'), at least three points.

Further, in step S8, the rotation angles of the eyeball optical axis arecomputed. When the equation (2 ) is modified by using the positions(Zd', Yp') and (Ze', Yp') of the cornea-reflected images, the rotationangles θz and 74y of the eyeball optical axis satisfy the followingequations:

    β×Oc ×sin θ=Zc'-(Zd'+Ze')/2'        (3)

    β×Oc sin θy=Yc'-Yp'+δY'             (4)

where Y' is a value for correcting the positions of image re-formationof the cornea-reflected images e' and d'. Actually, such positions aredisplaced to shift in a Y axis direction with respect to a Y coordinateof the center of curvature O of the cornea 21 on the photo-electricelement array 6, since the infrared light emitting diodes 5 are disposedin a direction perpendicular to the arrayal direction of thephoto-electric element array 6 with respect to the light receiving lens4. This displacement is corrected by the value δY'.

In step S9, the eyeball determination circuit included in the fixationpoint position detection circuit 109 determines whether an observer'seye peeping through the viewfinder 101 is the right eye or left eye inaccordance with, for example, a distribution of the computed rotationangle of the eyeball optical axis.

In step S10, the visual axis correction circuit corrects a visual axison the basis of the eyeball determination information and the rotationangle of the eyeball optical axis.

In step S11, the fixation point detection circuit computes a fixationpoint on the basis of an optical constant of the finder optical system.

In this manner, the processing operation for detection of the visualline is performed. The above-mentioned scheme of the visual linedetection, however, has been associated with the following drawbacks.

When operator's visual line information on a viewfinder picture plane isutilized for control of a video camera, a photo-electric device for usein visual line detection detects a video signal which is of a reflectedimage of the eyeball by infrared light for visual line detection, and avideo signal which is of a reflected image of the eyeball by theviewfinder light as well. As a result, it will be the cause of decreasein signal-to-noise ratio (S/N) and thus of decrease in visual linedetectible accuracy.

Specifically, in a case where strong infrared light, for example,sunlight and so on, is contained in the camera subject image, it willnotably appear, as shown in FIG. 9, as noise on an output of thephoto-electric element array. Thus, it will be the cause of decrease invisual line detectible accuracy.

In view of this matter, the finder picture plane 102 according to thepresent embodiment is provided with display means having characteristicsas follows.

FIG. 10 depicts a spectral characteristic involved in the finder pictureplane 102 using a black-and-white small Braun tube of display means anda spectral characteristic of light emitted from the infrared lightemitting diode 5.

In FIG. 10, generally, the infrared light emitting diode 5 has a peakvalue in a gain between wavelength 800 nm-1000 nm.

The finder picture plane 102 used in the present embodiment is providedwith a spectral characteristic having a distribution, as shown in FIG.10, such that the gain is rapidly increased below wavelength 700 nm.

Consequently, according to the finder picture plane 102 used in thepresent embodiment, even if a camera subject, which is strong ininfrared intensity, for instance, the sunlight, is photographed, it doesnot appear on the finder picture plane 102 as the infrared light, thatis, light having a peak value in a gain between wavelength 800 nm-1000nm. Hence, it is not mixed as infrared noise with the output signal ofthe photo-electric element array 6. Thus, it is possible to increase thevisual line detectible accuracy.

While the present embodiment shows the use of the finder picture planeusing a black-and-white small Braun tube, the present invention is notrestricted to such a use. For example, a finder picture plane using acolor liquid crystal display may also be applicable to the presentinvention, and it is sufficient to provide a spectral characteristichaving no influence on light of the infrared light emitting diode 5.

FIG. 11 depicts, by way of example, a spectral characteristic of lightemitted from a finder picture plane 102 using a color liquid crystaldisplay having no influence on light of the infrared light emittingdiode 5 and a spectral characteristic of light emitted from the infraredlight emitting diode 5.

The spectral characteristic of light emitted from the finder pictureplane 102 using the color liquid crystal display has a distribution suchthat the gain is rapidly increased below wavelength 700 nm.

Therefore, similar to the finder picture plane using a black-and-whitesmall Braun tube, the finder picture plane 102 using the color liquidcrystal display also has no influence on light emitted from the infraredlight emitting diode 5.

Hence, the light of the finder picture plane using the color liquidcrystal display is not mixed as infrared noise with the output signal ofthe photo-electric element array 6. Thus, it is possible to increase thevisual line detectible accuracy.

A video camera according to the second embodiment of the presentinvention, which utilizes the visual line detection scheme, will bedescribed hereinafter.

FIG. 12 is a block diagram schematically showing an arrangement ofessential portions of a video camera according to the second embodimentof the present invention, wherein the same parts are denoted by the samereference numerals as those of FIG. 3, and the explanation thereof willbe omitted.

In FIG. 12, reference numeral 3 denotes a light projection lens; 7 aneye-point half-mirror; 8 visible-light cut filter; 114 an image pick-upcircuit for converting a camera subject image into a video signal in theform of an electrical signal; 115 a shutter speed selection circuit forselecting a shutter speed; 116 a focus mode selection circuit forselecting a focus mode; and 117 a white balance mode selection circuitfor selecting a white balance mode.

Infrared light radiated from an infrared light emitting diode 5 isreflected a the half-mirror 7, and is further reflected at thehalf-mirror 2 to irradiate or illuminate an observer's eyeball 201 nearthe eye point E.

The infrared light reflected from the eyeball 201 is reflected at thehalf-mirror 2, transmitted through the half-mirror 7 and then convergedthrough the light receiving lens 4 so as to form an image on thephoto-electric element array 6, while eliminating visible light by thevisible-light cut filter 8.

The fixation point position detection circuit 109 is implemented withsoftware of a micro-computer on the basis of a flow described after.

Next, a flow for detecting a fixation point according to the secondembodiment will be described.

FIG. 13 is a flow chart for detection of the fixation point according tothe second embodiment. FIG. 14 is an explanatory view illustrating areflected image from the eyeball projected on planes of a plurality ofphoto-electric element arrays of the photo-electric element array 6,wherein the same parts are denoted by the same reference numerals asthose of FIG. 1, and the explanation thereof will be omitted.

In FIG. 14, Za', Zb' and Zd' denote positions of images associated withthe edge portions a and b of the iris 23 and the cornea-reflected imaged' respectively; c' a center position of the pupil 24; Yb' and Ya' the Ycoordinates of upper and lower ends of the pupil circle, respectively;and Yd'the Y coordinate of the cornea-reflected image d.

Referring to FIG. 13, first, the cornea-reflected image coordinate Zd'shown in FIG. 14 is detected (step S21). Next, boundary pointcoordinates Zb', Za', Yb' and Ya' between the iris 23 and the pupil 24are detected (step S22).

In Step S23, the pupil center c' is computed based on the detectedvalues obtained by the preceding steps.

In step S24, a displacement angle θ of the eyeball is computed based onthe data obtained by the preceding steps. The displacement angle θ iscomputed with respect to two-kind ones in a Z-X plane (horizontaldirection) and Z-Y plane (vertical direction).

In step S25, the fixation point is computed on the basis of thedisplacement angle finally obtained.

Next, the second embodiment will be described in operation, by way ofexample, as to a case where a shutter speed is changed over.

The shutter speed is set up to 1/60 second in an initial state. Now, ifthe shutter speed is changed over to, for example, "1/100 second" by theshutter speed selection circuit 115, the shutter speed indication "1/100second" is combined, by the fixation point display processing circuit103 at the fixation point position detected by the fixation pointposition detection circuit 109, with the video signal outputted from theimage pick-up circuit 114, and then the composition is displayed on thefinder picture plane 102 of the electronic viewfinder 101.

The fixation point display processing circuit 103 is provided with atimer, under the control of which the shutter speed indicationdisappears after the lapse of a predetermined time.

In this manner, the shutter speed is displayed at the fixation pointposition, and thus it is possible to change over the shutter speedwithout taking an operator's eye off a camera subject image on anelectronic viewfinder.

Likewise, with respect to selection of a focus mode (automatic ormanual), selection of a white balance mode (automatic or manual), and soon also, they may be displayed on a similar basis. It is of coursepossible to provide an arrangement in which mode indications other thanthe above-mentioned indications are displayed at the fixation pointposition on a similar basis as discussed above.

The finder picture plane 102 involved in the second embodiment is alsoprovided with a spectral characteristic as described in the firstembodiment.

As described above, according to the present invention, informationconcerning a video camera photographing is displayed in such a mannerthat a visual line of the eye peeping through an electronic viewfinderunit is detected by visual line detection means, and the information isdisplayed together with an image of the camera subject at the positionof the visual line on the finder picture plane. Accordingly, there is noneed to take the visual line off the camera subject image of the finderpicture plane, so that the necessary information display can be readilyread. Thus, it is possible to provide a video camera excellent in anoperational efficiency, releasing an operator from the trouble such asoverlooking of the necessary information and warning, and losing of ashutter opportunity due to removal of the visual line from the camerasubject image, etc.

Further, according to the present invention, a spectral characteristicof light emitted from the finder picture plane 102 is a spectralcharacteristic having no influence on light emitted from illuminationmeans for use in visual line detection which is contained in visual linedetection means. Hence, the view-finder light contains no infraredlight, so that infrared noise can be removed from the output signal ofthe photo-electric device for use in visual line detection. Thus, it ispossible to provide a video camera capable of detecting the visual linewith higher detection accuracy.

It is apparent that the invention may be implemented with alternationswithout departing from the essential scope. While the embodimentsdescribed and illustrated above employ a scheme in which infrared lightis projected to an operator's eye to detect his or her visual line,there may be employed, for example, such a visual line detection schemethat an image on the eye is taken in with an image pick-up device and soon without projecting infrared light beam, and the visual line isdetected from the taken-in image pick-up signal.

In other words, the foregoing description of the embodiments has beengiven for illustrative purposes only and not to be construed as imposingany limitations in every respect.

The scope of the invention is, therefore, to be determined solely by thefollowing claims and not limited by the text of the specification and,alternations made within a scope equivalent to the scope of the claimsfall within the true spirit and scope of the invention.

What is claimed is:
 1. An electronic apparatus, comprising:(A) detectingmeans for detecting a position of visual line of sight of an observer ina pre-determined field and providing output signals indicative of saiddetected positon; (B) illumination means for use in visual linedetection by said detection means; (C) a monitor, adapted toelectrically display in said predetermined field an image, having aspectral characteristic which is substantially set to have no influenceon a light emitted from said illumination means; (D) generating meansfor generating signals containing character display data indicative of awarning of an abnormal condition concerning an operation of saidelectronic apparatus; and (E) display processing means for receivingsaid signals containing said display data and displaying said displaydata on the monitor at said detected position of said observer's visualline of sight.
 2. An electronic apparatus according to claim 1,wherein:said monitor is an electronic viewfinder.
 3. An electronicapparatus according to claim 2, further comprising image pick-up meansfor converting an image of a subject into an electric signal.
 4. Anelectronic apparatus according to claim 1, wherein said detecting meansprojects light emitted from said illumination means onto an operator'seyeball, and detects the operator's visual line by using a reflectedlight from the operator's eyeball.
 5. An apparatus according to claim 1,wherein said display data includes character data.
 6. An apparatusaccording to claim 1, wherein said display data includes power sourceinformation.
 7. An apparatus according to claim 1, wherein said displaydata includes speed information.
 8. An apparatus according to claim 1,wherein said illumination means emits infrared light.
 9. An electronicapparatus being capable of using with a line of sight detecting devicehaving detecting means for detecting a position of a visual line ofsight of an observer in a predetermined field and providing outputsignals indicative of said detection position, illumination means foruse in visual line detection by said detection means, comprising:(A)generating means for generating character display data indicative of awarning of an abnormal condition concerning an operation of saidelectronic apparatus; (B) display, adapted to electrically display insaid predetermined field the display data, having a spectralcharacteristic which is substantially set to have no influence on alight emitted from said illumination means; and (C) display processingmeans for displaying said display data on the display at said detectedposition of said observer's visual line of sight.
 10. A monitoraccording to claim 9, wherein said display data includes character data.11. A monitor according to claim 9, wherein said display data includespower source information.
 12. A monitor according to claim 9, whereinsaid display data includes speed information.
 13. An apparatus accordingto claim 9, wherein said illumination means emits infrared light.